Marker auxotrophic

Schneider, J.C., Jenings, A.F., Mun, D.M. et al. (2005) Auxotrophic markers pyrF and proC can replace antibiotic markers on protein production plasmids in high-cell-density Pseudomonas fluorescens fermentation. Biotechnology Progress, 21 (2), 343-348. 

A specially constructed cross (1-41-5 x 1-34-8) of N. crassa has been used to determine the ability of agents to produce meiotic nondisjunction.11+7 The parental strains were heterozygous for four auxotrophic markers on chromosome 1 prototrophic disomies can be selected by plating ascospores on minimal medium. 

Fig. 2. Map of the Haloferax volcanii genome (top) the chromosome (bottom) the plasmids. Cosmids are represented by arrows, site-rich regions (oases) by heavy line, and markers placed by hybridization with unique probes are shown inside the circle (all from ref. [15]). Outside the circle are the results of probing with repeated sequences (ISH51, D), with labelled tRNA, 7S and ribosomal RNAs and (outermost) auxotrophic markers mapped by complementation. From ref. [86].

As an example of the application of these new approaches, we will examine the yeast two-hybrid system for the identification of protein-protein interactions within a cell. This system consists of a yeast genetic assay in which the physical association of two proteins is measured by the reconstitution of a functional transcriptional activator to drive a reporter gene such as P-galactosidase or an auxotrophic marker for selection ° (Figure 5.2). In general. 

Reporters HIS3 (an auxotrophic marker, the induction of which enables yeast cells to... 

S. cerevisiae laboratory strains have been selected for unicellular growth and multiple genetic markers, mainly auxotrophies, to enable easy selection. It has become evident recently that auxotrophic markers impair specific growth rate, chronological hfespan [28], and tolerance to high ethanol concentrations [29]. Therefore, it appears advisable to use wild-type strains for industrial production rather than (auxotrophic) laboratory strains. For many other yeast species, this is less of a concern as most of their laboratory strains are nearly wild type. 

Over the past 30 years, a wide range of selection markers have become available for P pastoris. Recessive markers, which require a mutation in the host genome that is complemented by the marker, mostly derive from amino acid or nucleotide synthesis pathways, as traditionally applied for other yeasts or bacteria as well (Table 19.3). The disadvantage of these auxotrophic markers is the possibility... 

Du, M., Battles, M.B., and Nett, J.H. (2012) A color-based stable multi-copy integrant selection system for Pichia pastoris using the attenuated ADEl and ADE2 genes as auxotrophic markers. Bioeng. Bugs, 3, Sl- Sl. 

Another problem is that virulence/pathogenicity is an essential prerequisite for successful matings since e.g. most auxotrophic mutants turned out to be non-pathogenic (Tudzynski et al., 1982), the use of auxotrophic markers in crosses is limited. 

Didek-Brumec, M., Gaberc-Porekar, V., Aladevic, M. and Sodid, H. (1993) Strain improvement of Claviceps purpurea by protoplast fusion without introducing auxotrophic markers. Appl. Microbiol. Biotechnol., 38, 746-749. 

Fig. 1. Schematic for cioning a bacteriai genome in yeast by homoiogous recombination of a yeast centromeric piasmid (YCp) vector with the genome at a double-stranded break created by restriction digestion at a unique site (caret). The vector contains a yeast centromere (CEN), repiication origin (ARS), and selectable auxotrophic marker (HIS of other) and is prepared by PCR ampiification. Not sites in the amplification primers allow clones to be sized by Not digestion and electrophoresis.

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